EP0159570A1

EP0159570A1 - A controlling method of a copying machine

Info

Publication number: EP0159570A1
Application number: EP85103718A
Authority: EP
Inventors: Yutaka Shigemura; Yoshinori Makiura; Mitsuya Ishito
Original assignee: Mita Industrial Co Ltd
Current assignee: Kyocera Mita Industrial Co Ltd
Priority date: 1984-03-30
Filing date: 1985-03-28
Publication date: 1985-10-30
Also published as: US4671643A; JPS60207173A; EP0159570B1; KR850006733A; KR890004403B1; DE3572409D1

Abstract

In a copying machine comprising a fusing device (5) which, by rotating a heating roller (53) and a press roller (54) in a mutually forcible contact, fuses a toner image on the copying paper (P) passing through the rollers (53) (54) and which is controlled to the wait-reset state capable of the copying operation and the wait state incapable of the copying operation in accordance with the conditions of the fusing device (5), a method for controlling the copying machine is established in such a way to set it in the wait-reset state after passing a certain fixed period of time after heating the heating roller (53) to a temperature T₃ higher than a setting temperature T₂ for fusing in the initial starting stage, and, after passing the initial starting stage, to raise the temperature from the low setting temperature T₁ in the wait state to bring it up to the setting temperature T₂ for fusing, and setting the wait-reset state even before reaching the setting temperature for fusing, but reaching it without fail when the edge of the copying paper (P) reaches the fusing device (5).

Description

BACKGROUND OF THE INVENTION

The present invention relates to a controlling method of a copying machine, more particularly, to a method for controlling the copying machine by the temperatures of a fusing device keeping it in a wait-reset state which is capable of the copying operation and in a wait state for preheating which is incapable of the copying operation.
In the copying machine of a type which heats and fuses a toner image transferred on the copying paper by the fusing device, should the copying operation is performed before the fusing device reaches a temperature high enough to fuse the toner, the toner image transferred specially on the copying paper will not be fused and the toner image will be readily damaged by hands, fingers and the like. The copying processing section, the conveying the copying paper section and so on are kept in a condition not to perform work as far as the temperature of the fusing device is still low. And the concrete measures to be taken are:

(1) Detecting that the fusing device has reached a preset temperature for fusing, a measure is taken for restoring the copying machine into the wait-reset state which enables to operates the copying operation section as well as the conveying the copying papers section and so on by detecting the signal, and
(2) a measure for restoring the copying machine to the wait-reset state after heating the fusing device for a certain period of time set by the timer.

According to the measure (1) mentioned above, inasmuch as the copying operation is available only after the fusing device reaches a preset temperature for fusing, a defective fusing can be precluded without fail. But it will take a long time for restoring the machine from the wait state to the wait-reset state. In other words, the time required to obtain copies after the copying operation is started by an operator will be protracted. Therefore, a greater improvement is desired from a clerical point of view, in which a speediness is seriously demanded.
On the other hand, according to the measure (2) mentioned above, while the setting time can be set relatively freely by the timer, etc., speeding of the copying operation can not be expected much, since setting of time is usually done with a sufficient safety factor considered in design so as not to cause defective copying. Moreover, despite the fact that a long heating time is required immediately after the start, a countermeasure taken so far is not sufficient and occasionally the trouble occurs in producing the defective copies. In order to obtain good fusing immediately after the start without fail, a long heating-up time for the fusing device is inevitably required after the initial starting state, thus the speeding-up of the copying operation may be greatly hindered.

SUMMARY OF THE INVENTION

It is an object of the present invention to accomplish a speedy copying operation, in particular, to reduce the time required to obtain good copies after starting a copying machine for the copying operation by an operator.
It is another object of the present invention to prevent a defective fusing, in particular, to prevent the defective fusing without fail in both of an initial starting state and a state thereafter.
It is a still further object of the present invention to accomplish a speeding-up of the copying operation simultaneously preventing a defective fusing.
The controlling method in accordance with the present invention is in a copying machine comprising a fusing device which, by rotating a heating roller and a press roller in a mutually forcible contact, fuses a toner image on the copying paper passing through the rollers, that the machine is provided with a wait-reset state capable of the copying operation and a wait state incapable of the copying operation by means of the conditions of the fusing device. It sets the machine to the wait-reset state capable of the copying operation by passing a certain fixed period of time after heating the heating roller to a certain setting temperature higher than a setting temperature for fusing in an initial stage of operation, and after passing the above-mentioned initial stage of operation, the machine is kept in the wait-reset state by heating the fusing device to a fusing temperature from a setting temperature lower than the setting temperature for fusing in the wait state , and after passing a fixed period of time which is shorter than a heating-up time by the time necessary for the copying paper to reach the fusing device, restoring the machine to the wait-reset state capable of the copying operation from the wait state for preheating.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic view clearly showing internal structure of a copying machine.
Fig. 2 is an enlarged longitudinal sectional view of a fusing device.
Fig. 3 is an electric circuit diagram.
Fig. 4 is a flow chart.
Fig. 5 is a time chart showing temperature variations of a fusing device, a wait state and a wait-reset state of said copying machine.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 is a longitudinal sectional view clearly showing internal structure of a copying machine of a type having a movable optical system. The inside of the copying machine body (1) is divided into an upper chamber (12) and the lower chamber (13) by a partition (11), wherein the optical system (2) is provided in the upper chamber (12) and the copy processing section (3) and a conveying section (4) of the copying papers are provided in the lower chamber (13). More particularly, the optical system (2) comprising a light source (21), No. 1 reflector (22), No. 2 reflector (23), No. 3 reflector (24), a lens (25) and No. 4 reflector (26), wherein an original on the contact glass (14) retained closely by an original cover (15) is scanned and exposed and an original image is formed on the surface of a photoreceptor drum (31) to be described later through a slit (27) on the partition (11) by moving the light source (21) and No. 1 through No. 3 reflectors (22) (23) and (24) in a direction shown by an arrow A, [however, a moving speed of No. 2 and No. 3 reflectors (23) (24) is set at half of the moving speed of the light source (21) and the No. 1 reflector (22)].
The copy processing section (3) is provided with an corona charger (32), a developing means (33), a transfer charger (34), a separation charger (35) and a cleaner (36) arranged in that order in the peripheral of the photoreceptor drum (31), which rotates on every copying operation in a direction shown by an arrow B, wherein an electrostatic latent image corresponding to the original image is formed by the optical system (2) mentioned above after the surface of the photoreceptor drum (31) being uniformly charged by the corona charger (32) with the rotation of the photoreceptor drum (31), the electrostatic latent image is developed into a toner image by the developing means (33), the toner image is transferred onto the copying paper (P) by the transfer charger (34), the copying paper (P) is separated from the photoreceptor drum (31) by the separation charger (35) and the toner remained on the photoreceptor drum (31) is recovered by the cleaner (36).
The conveying section (4) for the copying paper comprises the feed rollers (41) (42), the paper feeding paths (43) (44), a resist roller (45), a conveying roller (46), a conveying belt (47), a fusing device (5) and a delivery roller (48) arranged in that order, wherein by selectively driving each of the feed rollers (41) and (42), the copying papers (P) are taken out one by one from the upper or the lower paper cassettes and directed toward the copy processing section (3) where the toner image is transferred thereon and delivered on the tray (18) after the toner image being heated and fused by the fusing device (5).
As shown in Figure 2, the fusing device (5) mentioned above includes a heating roller (53) and a press roller (54) mounted rotatably to the upper and lower frames (51) (52) facing in opposition to each other vertically. In more detail, the heating roller (53) comprises a cylindrical body (55) formed by the material such as aluminum and the like having a high heat conductivity and provided with a heating source (56) such as a heater, etc., therein, and a teflon coated layer (57) on the outer surface thereof, while the press roller (54) comprises a cylindrical body (58) formed by the metal and the like of which outer surface is provided with a silicone rubber layer (59), and by rotating at least one of two rollers by a driving means (not shown) the other roller follows the rotation reversely. Further, a temperature sensor (60) such as a thermistor, etc. is provided in a contacting or adjacent state to the outer surface of the heating roller (53) together with a separating claw (61) for preventing the copying paper (P) from being rolled into the heating roller (53).
Figure 3 shows an electric circuit diagram, which is adapted to control a key board and a controller (71) and the heat source (56) by the output signal from a control circuit (70) by connecting the resistors (62) (63) (64) and (65) in series, providing reference voltages different with each other to the comparators (66) (67) and (68) by the node voltage of each resistor, providing a same comparison voltage to the comparators (66) (67) and (68) by the node voltage of the temperature sensor (60) and the resistor (69) and impressing the output signals from each comparator (66) (67) and (68) to the control circuit (70). The control circuit (70) mentioned above includes a first timer for setting the time at the initial starting stage and a second timer for setting the time after the preheating.
Accordingly, comparators (66) (67) and (68) impress the detecting signals to the control circuit (70) in each different detecting temperatures and the keyboard and the controller (71) and the heating source (56) may be controlled in accordance with these signals.
The controlling method of the copying machine constituted as mentioned above will be described with reference to a flow chart in Figure 4.
When a power switch (not shown) is turned on, the copying machine is set in the wait state (incapable of the copying operation) as step (1), the first timer for setting the time at the initial starting stage is set at time tsl = t2-tl (Ref. to Fig. 5) as step (2) and a timing operation is started as step (3). Then as step (4) whether in the preheating mode (a mode to retain the temperature of the fusing device at the setting temperature a little lower than the fusing temperature and to enable an immediate rise to the fusing temperature) or not is judged. Since the preheating mode is not attained immediately after the initial starting stage, if the timing of the first timer has reached the setting time tsl is judged at step (5), if so then as step (6) if the temperature has been reached, the setting temperature T2 for fusing is judged, if not then as step (7) if the temperature has reached the setting temperature T3 higher than T2 is judged. Then, when the temperature has not reached the setting temperature T2 or T3, the heater as the heating source (56) is energized as step (8) and when the temperature has reached the setting temperature T2 or T3 the heater is deenergized as step (9) and the wait state is reset as step (10) and the decisions and processings from step (4) onward will be repeated thereafter.
On the other hand, if it is judged that the preheating mode has been attained as step (4) the copying machine is set in the wait state as step (11), the timing operation of the first timer is stopped as step (12), judged as step (13) if the temperature has reached the setting temperature Tl lower than T2. If so the heater is deenergized as step (14) and if not the heater is energized as step (15) and judged again as step (16) if the preheating mode has been attained.
Then, if "Yes", the decisions and processings from step (13) onward will be continued. And if "No", judging that the timing by the first timer has reached the setting time tsl as step (17), and if not decisions and processings from step (7) onward will be repeated and if so the second timer is set to a difference ts2 = (t6-t4) - (t6-t5) = t5-t4 between the timer (t6-t4) necessary to heat from Tl to T2 and the time (t6-t5) necessary for the apex of the copying paper (P) to reach the fusing device (5) in the copying operation and simultaneously the timing operation is started and as step (19) the heater is energized, as step (20) judges if the timing by the second timer has reached ts2 = t5-t4, if not the above operations are continued in the wait state till the attainment and thereafter as step (21) the wait state is reset and the decisions and processings from step (6) onward will be repeated.
Figure 5 shows the temperature variations of the fusing device (5) in the above operations and the variations of states between the wait state and the wait-reset state of the copying machine proper, wherein the surface temperature of the heating roller (53) rises rapidly by energizing the heater at the initial starting stage and after reaching the setting temperature T3 (e.g. 195°C) higher than the setting temperature T2 for fusion, it retains the setting temperature T3 mentioned above till the time tsl set by the first timer has past and heats the press roller (54) and so on rapidly toward the setting temperature T2. During this period, since the fusing device (5) is not heated sufficiently on the whole, the copying machine is retained in the wait state.
After the setting time tsl mentioned above has past, first, the heater is deenergized and cooled to the setting temperature T2 (e.g. 185°C) for fusing and retained at the setting temperature T2 thereafter. During this period, since the fusing device (5) is in the state sufficiently heated on the whole, the copying machine is in the wait-reset state, so the copying operation can be performed by operating a print key. On the other hand, when the wait-reset state has continued for a fixed period of time or a fixed period of time has past after the completion of the copying operation, the fusing device (5) is cooled down to the setting temperature Tl for preheating lower than the setting temperature T2 for fusing and is kept at Tl thereafter and the copying machine is retained in the wait state.
When performing the copying operation thereafter by resetting the wait state, firstly, a key, not shown must be operated to energized the heating source (56), then the fusing device (5) will start rising toward the setting temperature T2 and before reaching thereto the copying machine will be set at the wait-reset state. Accordingly, the copying operation can be performed by operating the print key thereafter, and since the fusing device (5) has surely attained the setting temperature T2 when the copying paper (P) reaches the fusing device (5), the defective copying can be completely avoided.
The present invention, as mentioned above, detects the temperature rise of the fusing device at the initial starting state, sets the fixed period of time in the wait state for preheating and sets the restoring time from the wait state to the wait-reset state at the fixed time shorter than the time necessary to heat the fusing device by the time necessary for the apex of the copying paper to reach the fusing device, therefore, the copying operation can be performed only in the state which insures the stable fusing by the sufficient temperature rise and the restoring time from the wait state for preheating to the wait-reset state capable of the copying operation can be shortened.
Further, the present invention is not limited to the above embodiment, but various changes and modifications in designs may be made within the scope not departing from the spirit thereof, for instance, it may be possible to provide a heat source inside the press roll or split the heat source in plural numbers and operate thereof selectively to the size of the copying paper and so on.

Claims

1. In a copying machine having a fusing device (5) which, by rotating a heating roller (53) and a press roller (54) in a mutually forcible contact, fuses a toner image on the copying paper (P) passing through the two rollers (53) (54),
a controlling method of the copying machine characterized in setting it to the wait-reset state capable of copying operation in the initial starting stage by passing a certain fixed period of time after heating the heating roller (53) to a certain setting temperature (T₃) higher than a setting temperature T₂ for fusing, and, after passing the initial starting stage, heating the fusing device (5) to a fusing tempe- rature T₂ from a setting temperature T₁ lower than the setting temperatur T₂ for fusing in the wait state mentioned above, and restoring it to the wait-reset state capable of the copying operation from the wait state for preheating after a fixed period of time shorter than the time necessary for a temperature rise by the time necessary for an edge of the copying paper (P) to reach the fusing device (5).

2. A controlling method for the copying machine as claimed in claim 1,
which starts heating a fusing device (5) by operating a key on an operation panel.